Cationic surfactant-based products such as anti-bacterial surface cleaners, fabric softeners, skin conditioners, hair conditioners, conditioning shampoos, among others, are often difficult to thicken with conventional thickeners. Many common thickeners such as xanthan gum, CMC (carboxymethylcellulose), carrageenan, and polyacrylates are anionic and therefore, can react with the cationic surfactants and cause precipitation of the cationic and thickener or reduce the efficacy of the cationic surfactant. Non-ionic thickeners such as hydroxyethylcellulose (HEC), hydroxypropylmethylcellulose (HPMC), and scleroglucan can provide viscosity in cationic systems, however in the case of HEC and HPMC, very little suspension properties are imparted to the fluid. In the case of scleroglucan, good suspension is often achieved but cost-in use can be prohibitive. Cationic thickeners such as polyquaternium 10 (cationic HEC) and cationic guar provide thickening in cationic systems but not suspension. Some forms of polyacrylates are effective at thickening cationic systems but they can be limited by pH, require high concentrations, have high cost-in-use, and often have narrow limits of compatibility with the cationic surfactants.
There is a need in industry to provide reliable suspension and viscosity to cationic surfactant systems. In these systems, the suspension of particles is often desired and such particulates might include abrasive agents, aesthetic agents (decorative beads, pearlescents, air bubbles, fragrance beads, etc.) or active ingredients (insoluble enzymes, encapsulated actives such as moisturizers, zeolites, exfoliating agents (e.g. alpha hydroxyl and/or glycolic acids or polyethylene beads), vitamins (e.g. vitamin E)) etc. or both.
It has been discovered that microfibrous cellulose (MFC), bacterially derived or otherwise, can be used to provide suspension of particulates in cationic systems. It was also discovered that the MFC may be used for this purpose with or without co-agents. When bacterially-derived microfibrous cellulose is utilized, cellular debris can be eliminated which can also result in transparent solutions at typical use levels with some formulations.
The microfibrous cellulose is non-ionic and is therefore unaffected by the cationic surfactants and maintains good suspension in these systems. Microfibrous cellulose is unique in its ability to function in these systems in part because it is dispersed rather than solubilized, thereby allowing its use in a wide range of pH and cationic surfactant concentrations without concern of precipitating the polymer due to “salting out” or other effects related to the competition for water.